Mortar Matching-Color/Composition

Mortar Matching & Analysis Services @ AMR
Labs

Welcome to AMR Labs.
Our focus is high quality masonry repair and the products and services needed to ensure the mortar repair is done right. Among these are
mortar testing,
mortar matching, pre-matched
mortar
mix, and other masonry repair products.

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Mortar Matching Services

Mortar Matching

Mortar matching is available in many forms, but not all methods of
matching mortar will work for any project. This is especially true
of the most commonly used method.

Mortar Matching Method

In the most common mortar matching method, there are assumptions
made in matching the mortar mix type, sand color and gradation, and
pigments, and the mortar is adjusted to provide a matching color
only. This practice is unacceptable in the repair and restoration of
masonry. Changing the
mortar composition, mortar type,
mortar
formula, sand color, sand gradation, or the formula of sand to
mix
ratio also changes the compressive strength of mortar, color and
texture of the mortar, and the ability of new mortar to bond with
old mortar. This generally results in re-cracking of the mortar
joints, chipping or spalling brick faces, and other damage to the
masonry walls.

Testing Mortar Samples to Match Mortar Color and Composition

Mortar Match Test

Mortar testingprovides a detailed
mortar analysis for matching old mortar. This
mortar matchingtest provides accurate usable data about the mortar and provides a detailed mortar formulafor matching the original mortar samples tested
from which the color can be adjusted to match as needed.

Custom Mortar Matching

Composition Matching of Existing Mortar Mix

Through analyzing and testing the
composition of samples of existing
mortar mix in a detailed mortar analysis, the complete mortar
composition formula is provided. This is the base for any custom
mortar color match or custom mortar matching. With
the base formula, minor adjustments can be made to adjust mortar
color for the rest of the mortar match without changing the mortar
type, crushing pressure, bond ability, or ratios. By custom matching
the mortar in this manner, you will reduce the inconsistencies of
color matching mortar, insure a better bond, and prevent damaging
the bricks with mortar that is too hard or soft.

Historic Mortar Matching

Matching Historic Mortar

In commercial and historic mortar restoration, it is common place to
get the mortar analyzed and matched through
testing samples of the
mortar. However, many of the testing methods are over priced and
inaccurate. The two most common used or recommended testing methods
for historic mortar analysis are the ASTM C-1324 and acid digestion
method of testing hardened mortar. These two mortar testing analyses
are the most and least expensive tests, but neither provide reliable
results.

Testing/Matching Mortar Composition

C-1324 is the most expensive type of
historic mortar analysis which
uses a spectrographic microscope to create a colorful image of the
mortar sample. This image is then visually inspected and a best
guess of proportions for the ratio is determined as the
composition
formula. There is a little more to it, but the accuracy of the
results is limited to the interpretation of the analyst and their
onsite experience as a mason. With their limited or likely
non-existent experience in the field, they are unable to provide a
quality interpretation of the testing data.

The acid digestion method for
testing mortar composition is the
least technical and least expensive mortar analysis, and is the most
commonly used method for testing old mortar. Acid digestion analysis
uses a balloon to capture the escaping gases released during
analysis. The balloon swells and is measured to determine the
quantity of the total binder materials. This test alone is not
capable of accurate results because, the results are still an
interpreted analysis of how much of the gas released is coming from
each binder material. This factor alone is problematic because the
sand aggregates tend to have a portion of cementious material that
contaminates the results. Some sands used are entirely cementious
materials. This doesn't happen often, but it does happen.

Matching Mortar Composition Mix

There is a better way to test the composition of mortar samples for
historic mortar matching, and it is not much more expensive than the
acid digestion test. This method is proprietary to AMR Labs and is
becoming more excepted for this use due to the accuracy of the
results. This testing method for
matching mortar composition
combines the results of some other astm testing methods such as the
C-109 crushing analysis, acid digestion, E-11 sand sieve analysis,
and some more scientific analyses where we collect additional data
from some of these other testing methods for validations.

One example of this is the amount of weight loss during the
digestion of mortar samples is cross referenced with the compressive
strength and mortar type and using the specific gravity of the
binder materials, we are able to validate the accuracy of the
results. This is a limited example because there are other factors
that change variables such as the size and shape of sand aggregates
changes the compressive strength of the mortar as much as the
ratio
of sand to mix.

Matching Existing Mortar

Match Existing Mortar Formula

Mortar matching through our complete
mortar analysis and
adding a detailed mortar color match provides a exact mortar formula for matching the existing mortar color and
composition. With this complete formula, we can manufacture bags of custom matched mortar
for your project. This is however limited to mortars using type S/SA
lime as we currently do not have a supplier for the historic lime.

Historic Lime Mortar

In the past, we provided the analysis report and the formula and
Virginia Lime Works provided the manufacturing of the historic lime mortars. We
have been told they are no longer around and we haven't found a
suitable replacement as yet. Places we have found that may assist
you if you need the historic lime mortar manufacturing are US
Heritage Group and Lime.org.

Type S/SA and Historic Lime

One of the most common questions asked is the difference between
historic lime and type S/SA lime in mortar. The simple answer is
they are both lime, but the historic lime mortar uses a larger
particle size and was sometimes not screened allowing large chunks
to be mixed into the mortar. This is easily recognized by the large
unmixed pieces of lime. Those that were screened are a little harder
to identify, but the type S/SA lime uses a very fine screen, and
tend to be used in harder mortar types and newer mortar more often.
If your mortar requires type S/SA lime, we can provide the
manufacturing of custom bags of pre-matched
mortar mix.

Pre-Matched Mortar

Custom Mortar Mix

Pre-matched mortars are bags of
mortar mix custom made to match the existing hardened mortar of your masonry repair. These bags are made using the formula from the mortar matching test.

We are in the process of building a list of onsite service providers
for the brick repair and mortar restoration services to assist you
in finding a local service professional. If you are a service
professional, please contact us to submit your company for inclusion
in this listing.

Architects/Engineers

We are in the process of building a list of local consultants to
assist customers involved in masonry preservation. If you are a
service professional, please contact us to submit your company for
inclusion in this listing.